Abstract
Concern about underwater noise has been increasing due to the high number of projects needing environmental impact assessment to know how the underwater environment could be affected by pollutant noise, especially when living beings are involved. Since in countries like Chile there is no current legislation about anthropogenic underwater noise, the main objective of this work was to face this topic in Chile. To achieve it, noise sources present in rivers from Valdivia City-located in south center Chile-were evaluated. Underwater and airborne noise emissions measurement, coming from a high number of anthropogenic noise sources, both mobil and stationary, were carried out using a field method. It uses a digital recorder through which the noise emitted from the evaluated source is recorded. Subsequently, using a software, the desired noise descriptors are obtained. Measurements were carried out both in summer and winter seasons, between December 2015 and December 2016. To have a database of sources as those assessed in this study, measured in field conditions and with low natural background-noise, takes a relevant value when working with mathematics models of acoustic prediction. The information we have to introduce into them must be as accurate and as similar as possible to those acoustic characteristics of the noise sources considered. It is important to state how necessary standardizing procedures used to measure and present results of under-water measurements appears now. There exists a wide variety of literature showing divergences regarding this. This work tried to bring into the area of underwater measurements techniques and considerations used in air measurements, since, strictly speaking, the change is only in the involved fluids.